1. Field of the Invention
Aspects of the present invention relate to a portable and scalable heat exchange system. More particularly, aspects of the invention relate to a high-efficiency water-to-water heat exchange system for providing an efficient, portable, and/or scalable heating and/or cooling source.
2. Background of the Technology
FIG. 1 shows an exemplary vapor-compression refrigeration cycle 2 used in many heat exchange systems, in which a refrigerant is circulated through a closed-loop compression and expansion cycle. As shown in FIG. 1, the refrigerant begins as a vapor at point A. During Phase 1 of the cycle, the refrigerant vapor is compressed and circulated by a compressor 10, resulting in a high-pressure, high-temperature refrigerant vapor. The electro-mechanical energy of the compressor 10 is also converted into heat energy carried by the refrigerant vapor, which exits the compressor 10 as a superheated vapor. During Phase 2 of the cycle, the superheated vapor passes through a condenser 20 where a heat exchange process pulls heat energy from the superheated vapor, causing the refrigerant to condense into a high-pressure liquid. As shown at Phase 3 of the cycle, the hot liquid refrigerant is then directed through a thermal expansion valve 30, which meters the flow of refrigerant to the evaporator 40 and usually results in a flash lowering of the pressure and temperature of the condensed hot liquid refrigerant. As a result, the low-pressure, low-temperature liquid or saturated liquid/vapor refrigerant enters the evaporator 40 during Phase 4 of the cycle, wherein a second heat exchange process draws heat energy from a heat source, such as water or air, to the refrigerant, causing the refrigerant to reach a saturation temperature and returning the refrigerant to the vapor state at point A. The cycle is repeated.
In many conventional residential heat pump systems, for example, for supplying heat, the heat exchanging condenser 20 extracts heat energy from the superheated refrigerant vapor during Phase 2 of the cycle by using a blower 50 to direct cool air across condenser coils carrying the hot vapor (see FIG. 1). The cool air conducts heat energy from the coils and the heated air is supplied by the blower through ducting, for example, to directly heat the home or residence. The evaporator, on the other hand, typically relies on the air temperature outside the home for drawing heat into the refrigerant during Phase 4 of the cycle.
For supplying cool air, the blower 50 may instead be used to direct hot air across evaporator coils carrying the cooler fluid refrigerant during Phase 4 of the cycle 2. The cooler fluid refrigerant conducts heat energy from the hot air, and the resulting cooler air may be supplied to the home. Under such circumstances, the condenser 20 relies on the outside air to cool the superheated vapor during Phase 2 of the vapor-compression cycle 2
In some conventional systems, the heat pump may be designed with a reversible valve and specialized heat exchangers, for example, allowing the vapor-compression cycle 2 to operate in either direction, with each heat exchanger serving as either a condenser or an evaporator. The cycle of the heat pump can thus be reversed, so that, depending on the desired climate, a single blower may be used to direct hot or cool air across coils, for example, carrying the cooler refrigerant fluid or the superheated refrigerant vapor, respectively.
A typical air-source heat pump, as described above, works harder to transfer heat from a cooler place to a warmer place as the temperature difference increases between the cooler and warmer places. Accordingly, the performance of an air-source heat pump deteriorates significantly, for example, during the winter months in a very cold climate, as the temperature difference between the air outside a home becomes significantly less than the desired temperature inside the home.
A ground source heat pump system, which typically extracts heat from the ground, or a body of water, may be used to counteract the effect of significant temperature gradients between the heat source and the heat sink. This is because the ground below a certain depth, and water below a certain level, maintains a fairly constant temperature year round, leading to generally lower temperature differentials throughout significant periods of the year, allowing for increased performance of the heat pump. As shown in FIG. 2, the vapor-compression cycle 2 described in FIG. 1 may be coupled with a ground source loop 3 that carries a heat exchange fluid, such as water, for example. The heat exchange fluid conducts heat while flowing through conduits 4 buried in the ground or sunk under a body of water 5. A portion of the heat carried by the heat exchange fluid in the conduits 4 is transferred to the cooler liquid refrigerant by conduction through a heat exchange process performed by the evaporator 40 during Phase 4 of the vapor-compression cycle 2. The refrigerant is vaporized, and the refrigerant vapor is then compressed during Phase 1 of the vapor-compression cycle. As described previously, a blower 50 may be used to direct cool air across condenser coils while carrying the hot vapor during Phase 2 of the vapor-compression cycle 2 in order to provide heat to the interior of a structure. Additionally, a heat sink loop 6 may be coupled with the condenser 20 to capture heat transferred from the heat exchange fluid during Phase 4 of the vapor-compression cycle 2, along with heat that is added through the electro-mechanical energy input by the compressor 10 during Phase 1 of the vapor-compression cycle 2, into a heat sink 60, which could be a tank of hot water, for example. The condensed refrigerant exiting the condenser 20 is then expanded during Phase 3 of the vapor-compression cycle 2 and the cooler refrigerant liquid enters the evaporator 40 once again to draw more heat from the heat exchange fluid flowing through the ground source loop 3.
A typical ground source system, such as the ground source loop 3 described above, is expensive to construct and can be extremely disruptive to install because thousands of feet of piping may need to be placed in horizontally dug trenches or wells dug vertically deep into the ground, to effectively tap into the thermal energy contained therein. And although the thermal conductivity of water is greater than that of the ground, generally allowing for less piping to be placed into a body of water, access to a body of water close enough to the home for the purpose of creating a ground source system is often unfeasible.
There exists a need for a heat exchange system which combines the efficiencies of the thermal conductivity of a fluid, such as water and a specially tuned vapor-compression cycle to produce an efficient, portable, and scalable heat exchange system for simultaneously providing heating and/or cooling.